Questions tagged [beam]

Questions about the theory and applications of structural elements designed to resist bending.

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23 views

Diagrams of forces and moments of a statically determinate structure

I'm having difficulties with calculating the distribution of forces and moments in a statically determinate structure shown below. I'm especially confused about the arc part. Will there be only ...
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3answers
73 views

Exactly what makes steel-concrete composite beam better than pure steel?

A composite action beam may have a concrete section the top, carrying the compression load, and steel at the bottom, carrying tension. But I have always thought that concrete had lower strength for a ...
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How many support beams/rods needed for a firewood storage cabinet

I am building a firewood storage cabinet which should support around 100-150 kg of firewood. The cabinet is made out of wooden boards (...
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3answers
71 views

Why is it said that the flange of an I beam carries most of the moment?

It is often said for I beams that the flange carries most of the moment subjected to the beam, while the web carries most of the shear force. The latter is obvious from pictures like above, showing ...
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44 views

Cantilever beam

I want to design a cantilever addition. Over the driveway so I can't add supports. I want to use the calculator here https://calcresource.com/moment-of-inertia-rect.html But I'm having trouble ...
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1answer
27 views

If an airfoil underwent horizontal loading, would it stiffen the airfoil? [closed]

I am designing a wing for a Vertical Takeoff and Landing aircraft. I am trying to choose a wingtip winglet for my aircraft. One of the option is a aft-swept wingtip winglet. However, this structure ...
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1answer
45 views

Boundary conditions for a cantilevered Timoshenko Beam

I am trying to find out the boundary conditions for above given Timoshenko beam. The boundary conditions that I have derived are $x_1 = 0$ $$ \overline{u}_2^L = 0 $$ $$ \phi_3^L = 0 $$ $x_1 = \...
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4answers
97 views

Deflection of a fixed-fixed pvc pipe under self weight

I would like to start by saying I am not an engineer, so I apologize if this question seems simpleminded. I am making a manual tarp reel from pvc pipe, and I am trying to decided whether to use ...
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1answer
41 views

How to calculate the force of a cantilever beam at a given point of deflection?

I have put together a simple cantilever beam using finite difference modeling according to the following standard wave equation $$ρAy_{tt} = -EIy_{xxxx}$$ where $ρ$ is density, $A$ is cross sectional ...
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1answer
46 views

Simple cantilever beam deflection - what is the simplest way to add a damper?

I am looking at a simple cantilever beam deflection: I understand the general expression for deflection/force would be: $y_s = \frac{Fx_s^3}{3EI}$ $F_p = \frac{3y_sEI}{x_s^3}$ If you were going to ...
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2answers
67 views

Multiple varying cross section beam with uniform loads

I have the following cantilever beam problem where I need to find the deflection of the tip at P. I tried to compute the deflection of the beam using Castignliano' s theorem as described in this ...
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67 views

Statically determinate system

The exercise is taken from linear algebra and its applications, prof. G. Strang Exercise 2.4.8 Truss I have already found that: m=n=8 → system is statically determinate, therefore solvable by ...
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double integration of continues beam to find the deflection at mid span [duplicate]

does any one know how to derive the deflection equation of a continues beam of three span of equal length and equal UDL load some of the steps of this explanation I didn't understand it Here's a link ...
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41 views

Continues beam deflection

does any one know how to derive the deflection equation of a continues beam of three span of equal length and equal UDL load Here's a link these two pictures shows my tries to solve the question
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1answer
24 views

Derivaiton of maximum deflection of a cantilever beam with intermediate load

I am trying to derive the maximum deflection of a cantilever beam. L is the length of the beam and a is the where force is applied. For the case 0<x<a, I use the method below and it gives me the ...
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3answers
104 views

How can deflection and spring constant of cantilever beam stack be calculated?

How can I calculate some properties of a stack of 2 bonded cantilever beams like in the image? Especially I am interested in the spring constant and deflection with force on random locations. However, ...
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Design of T-Beam

Please design a T-beam section size such that hf ≥ 125 mm, bw ≥ 200 mm, be ≥ 500 mm, d ≥ 300 mm, the concrete f'c strength is 25 MPa; the calculated concrete shear strength Vc that can be provided is ...
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1answer
64 views

How to check if bending moment diagram is correctly drawn

EDIT: I will state my test problem description and then my solution. But before that, I would like to apprise you of the absence of the actual description given during test (which happened in Zoom and ...
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1answer
30 views

Where does the equation for shear stress of a rectangular beam (3/2 V/A) come from?

I am writing a report and need to reference every equation used. I am using the equation for shear stress in a rectangular beam of tau = 3/2 * V/A but am not sure where it came from or what textbook ...
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1answer
71 views

What is meant by the rotation capacity of a cross section?

I'm reading about classification of beam cross sections here. It is said: The ratio of the ultimate rotation to the yield rotation is called the rotation capacity of the section. The yield and the ...
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75 views

Large deflection of a non prismatic cantilever beam under distributed load

Here's what I got trying to calculate the large deflection of a cantilever beam with two different cross sections under a uniformly distributed load: From the figure, the shear force is: $$ V(s) = q(...
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1answer
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“Heavy-duty” or not, can my drawer slides really support this weight?

Okay, so recently I got a Dewalt 735 Thickness Planer. It's great at what it does. (It even LOOKS like it's ready to consume the tender flesh of lumber, like some twisted Victorian lumberjack... ...
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1answer
44 views

Steel beam size

I'm a customer not an engineer! I had 2 sets of drawings for a project to put in bi fold doors. The original drawing had a beam of 230mm and then the engineer sent a revision with a beam 260mm. The ...
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1answer
49 views

Linear Motion Stage with Offset Loading Problem

I'm currently developing a linear motion system which will have to withstand a large offset load (see image below). There will be two rails, each with a carriage on, which will be connected by a beam/...
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2answers
67 views

Can you use an accelerometer to measure beam deflection under static loading?

With an appropriately collocated accelerometer is it possible to retrieve lateral deflection of a beam under static loading. The beam will be loaded and then deflect until it reaches equilibrium with ...
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4answers
91 views

Swing safety: maximum load of beam (supported at one end, free with load on the other)

My husband and his dad built a fort for our two boys. Coming off of one side of the fort is a 4x6 wooden beam with a tire swing attached at the end. It is supported on one side by the fort, but not ...
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1answer
167 views

How to plot bending moment diagram from shear force diagram

With conventions that I adopted shown below I drew roughly the shear force and bending moment diagram of a simply supported beam with concentrated load at the middle. Now while drawing I drew both ...
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1answer
53 views

Optimal placement of two support points along a wooden beam

Assuming a beam that is supported at 2 points as per attached image, what would be Lc (length center) and Lo (length overhang) for maximum strength. (or load bearing capability) For actual material ...
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1answer
40 views

Estimation of Beam Displacement from Acceleration

Hi Engineering Exchange, I have a beam with pinned-pinned boundary conditions (free to rotate but not free to translate). A legacy computer analysis provided me with the maximum mid-span acceleration ...
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7answers
4k views

Is it structurally sound to cut an I beam to a T on one end?

I'd like to confirm whether the replaced beam in the attached picture is structurally sound given the end was cut to a T instead of an I. I had a qualified structural engineer approve the work but I'm ...
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1answer
95 views

Beam for shop gantry

I have a small machine shop and need to size a beam for a gantry crane. The design is a 4 post fixed design with 2 horizontal beams running parallel across the shop ends with 1 beam to be mounted ...
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2answers
68 views

Beam buckling criterion?

If I have an I beam which I subject to some bending load, how can I calculate when the thinner middle part of the I beam will buckle? I though I could use Euler's critical load formula here, but it's ...
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1answer
73 views

Limits of Euler-Bernoulli Beam Theory for Wide Plate in Flexure?

I'm looking for established limits or rules of thumb for the validity/accuracy of Euler-Bernoulli beam equations for particularly wide "beams". For example, a simply supported rectangular ...
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1answer
22 views

Moment Arm: What dia.(3“ or 4”) Alum pole 10ft long (thickness .125) will support a load 200 or 300lb pulling at 90 degrees at the end of the pole?

I am trying to determine which diameter (3" or 4") metal pole I need to support a 20ft x 20ft pool shade tarp. I can use either steel or aluminum (aluminum preferred). The wall thickness ...
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1answer
72 views

Torsion and Bending stress calculated from deflection

I need help to check a calculation I did. I want to know if it is possible to use this method or if I am using an assumption which is wrong. Let me explain the problem, a beam with length $l$ is ...
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1answer
50 views

simply supported beam with a midspan load

First off non-engineer apologies, A plate of 5251 Aluminium is used to support the load of a centrally seated human I estimate a load of 1 kilonewton. The beam measures a length of 1000mm, 100mm wide. ...
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47 views

Deflection of a cantilever beam composed of separate (not bonded) planks Uniform load

This is related to this question It is the case of a simple cantilever beam having a uniform rectangular cross-section. cantilever beam composed of separate planks - taken from The question in the ...
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1answer
684 views

What is the difference between W, S, I, H sections?

W and H sections look pretty much the same. S and I sections have their flanges rounded. What difference does this rounding make, why would an S-section be used instead of W-section for example?
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How to choose the dimensions for a prestressed I-beam?

I need to design a simply supported symmetric I-beam (for a school problem). However, I can't find much information about the selection of the section or if there exist any standards for that. the ...
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1answer
36 views

steel beam type and size for a clothesline

I have four posts in a square formation. Posts are also square. I want to bolt a beam between two posts on the left and a beam between two posts on the right, and than run some wire between the beams. ...
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2answers
79 views

Do the floorboards in timber beam floors have a structural function?

Timber beam floors with perpendicular timber floorboards as indicated in the drawing below are common throughout northern Europe. The floorboards are nailed onto the beams and are quite substantial ...
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1answer
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Centroid of unsymetric bending in T-section

Can anyone please explain how this 24 is coming while calculating the x-cordinate of the centroid.
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125 views

Maximum induced bending stress within the beam

The Maximum induced bending stress within the beam. Given that: $$\frac{My}{I}$$ The beam depth is 300mm, the width is 150mm. The beam is an I section beam with a 5mm wall thickness. My ...
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75 views

RHS beam deflection with support on one end

A 1400 mm long galv steel beam, size 40x20x2. 80 mm of the beam on one end is welded in flat position to a platform. How much weight can I put safely on the other end? What if instead of being flat ...
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Pin connection on beam - FEA analysis

I am establishing a MatLab FEA code for determining the stiffness of a structure. Diagram of the structure is added below. I have established a code for determining the stiffness of the structure, but ...
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2answers
110 views

Boundary conditions for this beam deflection problem

consider the diagram above. I know that deflection is described by the equation $$EI\frac{d^4y}{dx^4}=p(x)$$ where $L$ is the length of the beam, $E$ is the Young's module, $I$ is the moment of ...
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777 views

Degrees of freedom of an internal hinge in plane beam?

What are the degrees of freedom of an internal hinge in a plane beam? I understand that the bending moment=0, does this mean there is no slope either? Or does it have both degrees of freedom of ...
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185 views

Sign convention for deflection and slope of beam?

What is the sign convention for deflection and slope of a beam as shown in the diagram below? When I derive the formula using Euler-Bernoulli for deflection and slope myself, I end up with - ...
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1answer
66 views

Why is there a row of circular holes in this concrete beam?

The reinforced concrete beam (approximate dimensions 36" x 18") shown in the image below has a row of circular holes at 3/5ths of the height of the cross-section at approximately 300 mm centres. My ...
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1answer
31 views

Shear flow for unequal leg channel

How does the sine part i.e. $\dfrac{\ell\sin(\theta)}{2}$ appear in the calculation of shear flow ($q$)? I mean, if I'm not mistaken, the sine part is the distance from the x-axis to point D, but how ...

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